Pump



Sept. 22, 1936. J. YOXALL I 2,055,396

PUMP Filed April 10, 1935 IF I Patented Sept. 22, 1936 PATENT [OFFICE PUMP Joseph Yoxall, 'D'eganwy, North Wales, assignor to Propello Inventions Limited, Chelsea, Lon- .don, England Application April 10, 1935, Serial No. 15,670 'In Great Britain January 8, 1935 5 Claims. (Cl.10338) The present invention relates to fluid pressure pumps and has for itschief object to provide a simple but effective construction of fluid pressure pump in which, when a predetermined fluid pres: sure is developed, that pressure is not exceeded, although the primejmover of the pump continues to drive the? pump and although no fluid is bypassed. It will be appreciated that it is generally impracticable in a constant-pressure pump to adjust the speed of the prime-mover to efiect'the desired control of fluid pressure, whilst to at tempt to secure control of pressure by by-passing fluid is wasteful and'involves unwanted leakage and heat-development in the pump system. Ac-

cording to the present inventiona fluid pressure pump comprises anoscillatable member adapted to move about a fulcrum to transmit an oscillatory pumping motion to one or more pistons, said fulcrum being mounted between a pair of opposed yieldable resilient members and being adapted to shift and compress one or other of said membersand so absorb a component of the motion of the oscillatable member when the pistons offer a predetermined resistance to said pumping motion.

In order that the invention may be readily understood and carried into effect, one embodiment thereof will now be described with reference to the accompanying drawing in which:

Figure 1 is a vertical section of a fluid pressure pump in accordance with the present invention, and Figure 2 is a section taken along line 2-2 of Figure 1.

The entire pump is contained in a housing 3, within which is mounted a, shaft l6. Shaft I6 is connected to a prime mover, not shown, and is provided with an eccentric sheave 45 upon which is mounted a strap 44/formed integral with lever 46. Lever 46 is pivoted at 8| in a tubular crosshead member 82 which is normally held against transverse movement by springs 83, 84 which bear against plungers 85, 86 in contact with said member 82. At its lower end, lever 46 is pivotally connected at 87 to a further cross-head 88 adapted normally to reciprocate longitudinally and transversely and cause to-and-fro movement of pistons 89, 90 fitted in cylinders 92, to constitute pumps for fluid. Springs 83, 84 are set by means of screwed plungers 93, 94 adjustable within casings 95, 96 in which the springs are housed, the springs 83, 84 being chosen of such strength or rating that pivot BI is normally restrained by said springs from transverse movement. Of the longitudinal and transversev reciprocatory movements of lever 46, the longitudinal component is absorbed by free longitudinal movement of cross-heads 82 and 88 within their respective slides (constituted by an enlarged portion 92a of pistons 89, 90 which may, as shown, be integral strainer.

with each other and y the ends 'cr pang-at 85, 86), whilst the transverse or lateral'compoment is absorbed by thelateral 'toand-jfro motion imparted by cross-head'88 to pistons 89,90, which perform their pumping function by virtue of the saidmotion. Since the bulk of the fluid pumped by these pistons will be required only occasionally (i. e. when the fluid is required to perform actual work, such as the control of pressure responsive means) and sincea few strokes of 10' the pistons 89, 90 suflice to raise the fluid pressure to the necessary operating pressure, it will be understood that'when this pressure has-been attained the fluid flow from cylinders 9|, 92 will be restricted, and that considerable resistance is 15" offered to the transverse oscillatory motion of cross-head 88; in consequence of this, the'pivo't 81 of lever 46 becomes the fulcrum'about which lever 46' performs its transverse oscillatory move ment, and this movement-is absorbed by cross 20' head 82 which then moves against thepressure of springs 83, 84-untilthe pressure of fluid within cylinders 9|, 92 is relieved and cross-head 88 is free to move transversely. The fluid pump is provided with disc valves 91, 98, and sucks fluid from a suitable supply or sump through a gauze There is thus provided a fluid pressure pump driven by a prime mover and having a spring-loaded fulcrum such that when the fluid reaches the required working pressure, the fulcrum yields and reduces the stroke of the pump to a minimum necessary to compensate for any leakage and for any supply of fluid as may berequired, the whole action of the pump being completely balanced, and thus quiet in working. In this way the known rather uneconomical springloaded by-pass arrangement is avoided in which fluid is pumped at all times in uniform full quantity but is Icy-passed when the pressure exceeds a predetermined value. In place of the eccentric 45 there may be used any like means such as one or more cams for providing the desired oscillatory motion of the lever 46. The positions of the pumps (89, 90, 92) and the yieldably resilient members (85, 86, 83, 84) may, if desired, be reversed, the latter being then disposed below the former, but the arrangement illustrated is preferred. Also, the springs 83, 84 may be replaced by other yieldably resilient members, such for example as pistons working within cylinders to which fluid is admitted.

The improved fluid pressure pump described above, is, of course, adapted to serve a large number of uses e. g. as a fuel pump for I. C. engines.

What I claim is:

l. A balanced, chatterless fluid pressure pump comprising'in combination an oscillatable lever, means for imparting oscillatory motion to said lever and including an eccentric strap connected to one end of said lever, a tubular cross-head pivsaid first-mentionedjcross-head and said strap,

a pair of opposed spring-loaded members between which said second cross-head is slidable,

each of said spring loaded membersyielding in turn to absorb a component of the motion of said lever when said pistons experience a predetermined resistance to reciprocatory motion 7 within said cylinders.

2. A balanced, chatterless fluid pressure pum comprising in combination an oscillatable lever, two cross-heads pivotally connected to said lever at s'pacedpoints thereon, an eccentric for imparting oscillatory motion to said lever, a pair of opposed'connected pump pistons in bearing engagement with one of said cross-heads, and a pair of opposed spring-loaded members in bearing engagement with the other of said crossheads, each of said spring-loaded members being compressed in turn to absorb a component of the motion of said oscillatable member when said pistons experience a predetermined resistance to reciprocatory motionv within said cylinders.

' [3. A balanced, chatter'less' fluid pressure pump comprising in combination an oscillatable member, two fulcrum members pivotally connected to said member at spaced points thereon, means for imparting oscillatory motion to said member, a pair-of opposed connected pistons. in bearing engagement with one of said fulcrum members, cylinders for said pistons, and a pair of opposed yieldably resilient members in bearing engagement with the other of said fulcrum members,

each of said resilient members being compressed ber, means for imparting oscillatory motion to said member, a pair of opposed connected pump pistons, a slidable connection between said oscillatable. member and said pistons, cylinders Within which said pistons reciprocate, opposed yieldably resilient spring members, and a slidable connection between said oscillatable member and said spring members, each of said spring members being compressed in turn to. absorb a component of the motion of said oscillatable member when said pistons experience a" predetermined resistance to reciprocatory motion within, said cylinders V 5. A balanced, 'chatterless fluid pressure pump comprising in combination an oscillatable member, means for imparting oscillatory motion to said member, apair of opposed connected pump pistons, a slidable connection'comprising'a member pivoted to said oscillatable member and slidable with respect to said pistons, cylinders within which said pistons reciprocate and opposed yieldably resilient spring members in bearing engagement with said oscillatable member, each of said spring members being compressed in turn to ab sorb a component of the motion of said oscillatable member when said pistons experience a predetermined resistance to reciprocatory motion within said cylinders.

JOSEPH YOXALL. 

